diff --git a/serial_posix.c b/serial_posix.c
index 34ac6fc..a49f6c8 100644
--- a/serial_posix.c
+++ b/serial_posix.c
@@ -463,6 +463,7 @@ serial_read (serial* device, void* data, unsigned int size)
 				timeout = 0;
 			else
 				timeout = device->timeout - elapsed;
+			timestamp = now;
 		}	
 	}